Since the specific target of each country for substitution of Halon fire extinguishing agents was put forth in Canadian Montreal Convention in 1987, all countries in the world have been committed to the research of new fire extinguishing techniques. Fire extinguishing techniques with high fire extinguishing efficiency and no environmental pollution are directions of our effort.
A gas fire extinguishing system, a powder extinguishing system, a water fire extinguishing system and the like are harmless to environment, so they are selected as substitutes of Halon fire extinguishing agents and are widely used. The fire extinguishing mechanism of the fire extinguishing systems of carbon dioxide, IG541 and inert gases mainly relies on physical fire extinguishing. The fire is put out by lowering the concentration of oxygen in the firing area. This fire extinguishing method would easily threaten human safety. The powder extinguishing system puts out a fire by spraying powder under the action of pressurized gas to contact flame and realize physical and chemical suppression effect. A water mist fire extinguishing system achieves the objects of controlling, suppressing and putting out a fire through triple actions of cooling, smothering, and isolation of thermal radiation by using water mist.
However, all these fire extinguishing systems need high pressure storage. Not only the volume is large but also there is a risk of physical explosion during storage. A document “Safety Analysis of Gas Fire Extinguishing System” (Fire Science and Technology 2002 21(5)) analyzes the risk of a gas fire extinguishing system and enumerates the safety accidents triggered by the stored pressure gas fire extinguishing system during use.
The existing thermal aerosol fire extinguishing agents are mainly type S and type K fire extinguishing agents. The comprehensive analysis of their performance and features indicates that their fire extinguishing mechanism is that the thermal aerosol fire extinguishing agents take a redox reaction through agent combustion to release a great quantity of gas and active particles and the goal of integrated chemical and physical fire extinguishing is realized through the chain scission reaction of the active particles and covering and smothering of a great quantity of gas. The disadvantage of the thermal aerosol fire extinguishing agents is that the thermal aerosol fire extinguishing agent will release a great quantity of heat while it takes the combustion reaction to release the thermal aerosol, which may cause a secondary combustion. In order to effectively reduce the temperature of the device and aerosol and avoid the secondary fire, a cooling system needs to be added. The cooling materials of the existing thermal aerosol fire extinguishing units can reduce the temperature of products, but they also greatly weaken the fire extinguishing performance of the products. In order to make up the loss on the fire extinguishing performance caused by the cooling system, many products either lower the fire extinguishing level or continuously increase the mass of the actual fire extinguishing agent, rendering the increase of product volume and the decrease of use efficiency, which results in a complex and cumbersome structure of the device, a complex technological process, a high cost, and a high nozzle temperature, which would easily cause injury to fire fighters.